1. Field of the Invention
The present invention relates to a storage management system and, in particular, to a volume allocating method in a technology for storage operation management on a Storage Area Network (SAN).
2. Description of the Related Art
The SAN effectively uses a large amount of data and, therefore, it is extremely widespread in recent years. The introduction of the SAN increases the flexibility of an information system in a company. However, a plurality of storage devices are connected via a fiber channel switch and this complicates the structure of the storage device. Further, the equipment setting of a system manager becomes complicated.
The central control of the storage devices causes the increase in data capacity of a single system manager. Further, this increases the types of service servers and the types of service application. In addition, the amount of data increases day by data and, therefore, the storage device is enhanced and the storage allocation to the service server is frequently executed.
In order to actually store data in the storage device, a logical area, a so-called volume needs to be allocated to the storage device. The allocation of volume needs not only the designation of storage device but also the designation of disk group in the storage device, namely, group of disks forming RAID structured by collecting a plurality of disk devices.
One well-known technology for central control of the complicated storage devices is disclosed in U.S. Pat. Publication No. 6,430,611 (Patent Reference 1). According to the technology disclosed in U.S. Pat. Publication No. 6,430,611, a computer for managing a data area in the storage device is connected to the storage devices connected to the SAN, and agents for collecting information on the storage devices operated therein are arranged. A single management server for communication with the agents is provided and, thus, it can manage the entire storage devices in a network (refer to the 56th line in the first paragraph to the 36th line in the second paragraph in U.S. Pat. Publication No. 6,430,611).
A plurality of volumes can be arranged in the single disk group and, therefore, the simultaneous access to a plurality of volumes in the single disk group reduces the individual volume performance. One technology for reducing the load of volume in the single disk group is disclosed in U.S. Pat. Publication. No. 6,535,954 (Patent Reference 2) (corresponding to Japanese Unexamined Patent Application Publication No. 11-296313). According to the technology disclosed in U.S. Pat. Publication. No. 6,535,954, the load is concentrated to the disk group and, when one disk control device has excessive load prior to the load of the disk group, the management of the disk group or volume shifts to another disk control device, thereby exhibiting the maximum performance of the disk group or volume (refer to the 17th to 27th lines in the third paragraph in U.S. Pat. Publication. No. 6,535,954).
Further, Japanese Unexamined Patent Application Publication No. 2001-184175 (Patent Reference 3) discloses a technology for storing the history of access information to the storage device and for forming a candidate of new logical-disk-structure based on the analysis result of the history information so as to restructure the logical disk structure in which the access performance is improved and the using efficiency of the disk area is increased.
The complexity of the structure of storage device complicates a volume management method. Therefore, the solution of the above problem is demanded.
However, U.S. Pat. Publication. No. 6,430,611 discloses that the single management server can monitor the complicated storage devices. However, a volume management method is not disclosed.
Further, according to U.S. Pat. Publication. No. 6,535,954, the maximum performance of the disk group is exhibited. However, there is a problem that a plurality of volumes are arranged in the disk group and the requested performance is not exhibited when the disk group has the load of the maximum performance or more.
When the number of accesses over the theoretical maximum performance of the disk group is requested to a plurality of volumes formed in the disk group, the disk group cannot satisfy the requested performance. Thus, preferably, upon allocating the volume, the disk group can be selected so as to prevent the excessive performance of the disk group by allocating the volume.
Further, the allocation of volume for requesting the higher performance needs the efficient allocation of volume so as to remain the disk group for non-allocation as much as possible.
The technology disclosed in Japanese Unexamined Patent Application Publication No. 2001-184175 pays attention to the increasing ratio of the used disk capacity. However, the candidate of the new logical-disk structure is not determined by paying attention to the performance and the reliability. Further, Japanese Unexamined Patent Application Publication No. 2001-184175 does not describe a method for systematically allocating the volume before operation while anticipating the deterioration in performance.